Method for forming a wind turbine foundation and related system for forming such a foundation

ABSTRACT

A method of forming a wind turbine foundation includes providing an anchor cage in an excavation pit, the anchor cage including an upper flange, a lower flange, and a plurality of anchor bolts extending therebetween. A first cementitious material is directed into the excavation pit so that the anchor cage becomes at least partially embedded in the material, which is allowed to cure to form a rigid body. A connecting element is selectively engaged with the upper flange and an actuating element is positioned in operative relation with the connecting element, the connecting and actuating elements positioned in non-contact relation with the anchor bolts. The actuating element is actuated relative to the connecting element to raise the upper flange from the rigid body into a leveled position. A second cementitious material is directed into a space beneath the raised upper flange and is allowed to cure to form a support layer.

TECHNICAL FIELD

The present invention relates generally to wind turbines, and moreparticularly to methods for forming wind turbine foundations.

BACKGROUND

Wind turbines are used to produce electrical energy using a renewableresource and without combusting a fossil fuel. Generally, a wind turbineconverts kinetic energy from the wind into electrical power. Ahorizontal-axis wind turbine generally includes a tower, a nacellelocated at the apex of the tower, and a rotor having a plurality ofblades and supported in the nacelle by a shaft. The shaft couples therotor either directly or indirectly with a generator, which is housedinside the nacelle. Consequently, as wind forces the blades to rotate,electrical energy is produced by the generator.

Horizontal-axis wind turbines may be anchored on land by securing alower portion, such as a lower tower flange, of the wind turbine towerto a foundation that extends into the ground. Conventional foundationsinclude steel-reinforced concrete structures arranged within anexcavation pit. The structure includes a centrally positioned steelanchor cage that is generally cylindrical and includes upper and lowerannular steel flanges arranged horizontally, and a plurality ofhigh-strength steel anchor bolts extending vertically between theflanges.

In conventional methods, the anchor cage is positioned within theexcavation pit and concrete is then poured into the pit so that theanchor cage becomes embedded within the concrete. Once the pouredconcrete cures, the upper flange is lifted from an upper surface of thecured concrete body to expose an annular trough. High strength grout isthen directed underneath the upper flange and into the trough, and isallowed to cure to form an annular grout support layer. The lower towerflange of the wind turbine is then lowered over the upper ends of theanchor bolts such that the grout support layer is positioned between thelower tower flange and the steel-reinforced concrete body of thefoundation. Nuts are tightened onto the upper ends of the anchor bolts,thereby tensioning the anchor bolts and maintaining the foundation underheavy compression, which is advantageous for counteracting overturningmoments exerted by the wind turbine during use. The grout support layerfunctions to maintain the wind turbine in a leveled orientation, and totransfer loads from the wind turbine tower to the foundation duringoperation. In that regard, it is desirable to form the grout supportlayer so as to define a level mounting plane at which the lower towerflange may be mounted to the foundation.

Conventional wind turbine leveling methods are generally performed byusing either the lower tower flange of the wind turbine, oralternatively the upper flange of the anchor cage, as an element fordefining the level mounting plane. For example, some known methodsinclude suspending and leveling the lower tower flange above thefoundation, and then filling grout onto an upper surface of thefoundation body up to a lower surface of the tower flange, and allowingthe grout to cure to maintain the wind turbine in a leveled position.Other known methods include raising the upper flange of the anchor cageto a leveled position above the foundation body, and then filling thegrout up to a lower surface of the upper flange. Once the grout cures,the tower flange may then be positioned on top of the foundation, withor without the upper flange of the anchor cage remaining in place, tomaintain the wind turbine in a leveled orientation.

The latter of these wind turbine leveling methods, in which the upperflange of the anchor cage is used to define the level mounting plane,exhibit various shortcomings. Accordingly, there is a need forimprovements in methods for setting wind turbine foundations andleveling wind turbines.

SUMMARY

A method of forming a wind turbine foundation according to an exemplaryembodiment on the invention includes providing an anchor cage in anexcavation pit formed in a ground surface. The anchor cage includes anupper flange, a lower flange, and a plurality of anchor bolts extendingbetween the upper and lower flanges. The method further includesdirecting a first cementitious material into the excavation pit so thatthe anchor cage becomes at least partially embedded within the firstcementitious material, and allowing the first cementitious material tocure to form a rigid body. The method further includes selectivelyengaging a connecting element with the upper flange and positioning anactuating element in operative relation with the connecting element, theconnecting element and the actuating element positioned in non-contactrelation with the anchor bolts. The method further includes actuatingthe actuating element relative to the connecting element and therebyraising the upper flange from the rigid body into a leveled position. Asecond cementitious material is directed into a space beneath the raisedupper flange, and is allowed to cure to form a support layer.

An exemplary system for forming a wind turbine foundation includes ananchor cage having an upper flange, a lower flange, and a plurality ofanchor bolts extending between the upper and lower flanges, the upperflange configured to engage a lower portion of a wind turbine. Thesystem further includes at least one leveling apparatus including aconnecting element engageable with the upper flange, and an actuatingelement operatively associated with the connecting element. The at leastone leveling apparatus is operated to raise the upper flange from therigid body to a leveled position, including engaging the connectingelement with the upper flange and actuating the actuating elementrelative to the connecting element without contacting the anchor boltswith the actuating element.

BRIEF DESCRIPTION OF THE DRAWINGS

Various additional features and advantages of the invention will becomemore apparent to those of ordinary skill in the art upon review of thefollowing detailed description of one or more illustrative embodimentstaken in conjunction with the accompanying drawings. The accompanyingdrawings, which are incorporated in and constitute a part of thisspecification, illustrate one or more embodiments of the invention and,together with the general description given above and the detaileddescription given below, serve to explain the one or more embodiments ofthe invention.

FIG. 1 is a perspective view of a wind turbine coupled to an exemplaryfoundation, shown schematically;

FIG. 2 is a perspective view of an anchor cage for use with a windturbine foundation according to an exemplary embodiment of theinvention;

FIG. 3A is a perspective view of an upper load distribution flange ofthe anchor cage of FIG. 2, having a plurality of arcuate segments shownin a disassembled configuration;

FIG. 3B is a perspective view of the load distribution flange of FIG.3A, showing the arcuate segments in an assembled configuration;

FIG. 4 is a top view of the assembled load distribution flange of FIG.3A;

FIG. 5 is a radial cross-sectional view taken along line 5-5 shown inFIG. 4 of the anchor cage of FIG. 2, showing a radial pair of anchorbolts received within protective tubes;

FIG. 5A is an enlarged view of FIG. 5, showing a nut and washer on anupper end of each of the anchor bolts;

FIG. 6 is a radial cross-sectional view of the anchor cage of FIG. 2,showing a radial pair of support rods;

FIG. 7 is an upper radial cross-sectional view of a wind turbinefoundation in the process of formation according to an exemplaryembodiment of the invention, and including a rigid body reinforced bythe anchor cage of FIG. 2, shown at an exemplary leveling location alongline 5-5 shown in FIG. 4;

FIG. 8 is an upper radial cross-sectional view similar to FIG. 7,showing nuts in a raised position on a radial pair of anchor bolts;

FIG. 9 is an upper radial cross-sectional view similar to FIG. 8,showing a leveling apparatus, including a leveling plate, in operativeengagement with the anchor bolts and nuts;

FIG. 9A is a perspective view of the leveling plate of FIG. 9;

FIG. 10 is an upper radial cross-sectional view similar to FIG. 9,showing the load distribution flange raised to a leveled position toexpose a trough;

FIG. 11 is an upper radial cross-sectional view similar to FIG. 10,shown at an exemplary grouting location along line 11-11 shown in FIG.4;

FIG. 12 is an upper radial cross-sectional view similar to FIG. 11,showing details of a material delivering device for delivering groutinto the trough through the load distribution flange;

FIG. 13 is an upper radial cross-sectional view similar to FIG. 12,showing the hopper mated with the load distribution flange;

FIG. 14 is an upper radial cross-sectional view similar to FIG. 13,showing delivery of grout into the trough through the load distributionflange.

FIG. 15 is an upper radial cross-sectional view similar to FIG. 14,showing a cured grout support layer within the trough;

FIG. 16 is an upper radial cross-sectional view showing the completedfoundation coupled to and supporting a lower tower flange of the windturbine;

FIG. 17 is a perspective view of an arcuate segment of an upper loaddistribution flange according to another exemplary embodiment of theinvention;

FIG. 18 is a perspective view of a leveling plate according to anotherexemplary embodiment, for use with the upper load distribution flange ofFIG. 17; and

FIG. 19 is an upper radial cross-sectional view showing operation of theleveling plate of FIG. 18 in combination with the upper loaddistribution flange of FIG. 17.

DETAILED DESCRIPTION

Referring to the figures, and to FIG. 1 in particular, an exemplaryhorizontal-axis wind turbine 10 generally includes a tower 12, a nacelle14 disposed at the apex of the tower 12, and a rotor 16 operativelycoupled to a generator 18 housed inside the nacelle 14. In addition tothe generator 18, the nacelle 14 houses miscellaneous componentsrequired for converting wind energy into electrical energy and variouscomponents needed to operate, control, and optimize the performance ofthe wind turbine 10. The tower 12 supports the load presented by thenacelle 14, the rotor 16, and other components of the wind turbine 10that are housed inside the nacelle 14. The tower 12 further operates toelevate the nacelle 14 and rotor 16 to a height above ground level orsea level, as may be the case, at which faster moving air currents oflower turbulence are typically found.

The rotor 16 of the wind turbine 10 serves as the prime mover for theelectromechanical system. Wind exceeding a minimum level will activatethe rotor 16 and cause rotation in a substantially perpendiculardirection to the wind direction. The rotor 16 of wind turbine 10includes a central hub 20 and a plurality of blades 22 that projectoutwardly from the central hub 20 at locations circumferentiallydistributed thereabout. While the exemplary rotor 16 shown hereinincludes three blades 22, various alternative quantities of blades maybe provided. The blades 22 are configured to interact with the passingair flow to produce lift that causes the rotor 16 to spin generallywithin a plane defined by the blades 22.

The wind turbine 10 may be included among a collection of similar windturbines belonging to a wind farm or wind park that serves as a powergenerating plant connected by transmission lines with a power grid, suchas a three-phase alternating current (AC) power grid. The power gridgenerally consists of a network of power stations, transmissioncircuits, and substations coupled by a network of transmission linesthat transmit the power to loads in the form of end users and othercustomers of electrical utilities. Under normal circumstances, theelectrical power is supplied from the generator 18 to the power grid asknown to a person having ordinary skill in the art.

As shown in FIG. 1, the wind turbine 10 is anchored to a ground surfaceG by securing a lower tower flange 24 of the wind turbine tower 12 to afoundation 26, shown schematically. The foundation 26 is recessed in anexcavation pit, or cavity, formed in the ground G. The foundation 26 andrelated components and steps of formation are described in greaterdetail below according to exemplary embodiments of the invention.

In summary, and as shown best in FIGS. 2 and 17, the completedfoundation 26 generally includes a rigid body 28, an anchor cage 30 atleast partially embedded within and reinforcing the rigid body 28, and agrout support layer 32 positioned between an upper load distributionflange 34 of the anchor cage 30 and an upper surface of the rigid body28. The lower tower flange 24 is coupled to anchor bolts 36 of theanchor cage 30 and is directly supported by the load distribution flange34, which in turn is supported in a level position by the grout supportlayer 32. Advantageously, the exemplary embodiments of the inventionshown and described herein provide unique features and steps forleveling the load distribution flange 34 so that the wind turbine 10 maybe anchored in a level and stable orientation. As used herein, the term“level” means generally horizontal, and more particularly, generallyorthogonal to the direction of gravitational force.

Referring to FIGS. 2-4, formation of the foundation 26 begins with theassembly of the anchor cage 30, which may be performed at the windturbine installation site. As shown best in FIG. 2, the assembled anchorcage 30 is generally cylindrical and includes the upper loaddistribution flange 34, a lower base flange 38, and a plurality ofcircumferentially spaced anchor bolts 36 extending between the upperload distribution flange 34 and the base flange 38. The upper loaddistribution flange 34 and base flange 38 may be arranged generallyhorizontally, while the anchor bolts 36 extend generally vertically andcouple the upper load distribution flange 34 to the base flange 38. Theupper load distribution flange 34 and base flange 38 may be generallycircular, and in particular annular, for example. The components of theanchor cage 30 may be formed of high strength steel, for example.

Referring particularly to FIGS. 3A-4, features of the upper loaddistribution flange 34 will now be described. Though not simultaneouslydescribed in detail, it will be appreciated that the base flange 38 maybe formed with similar structural features.

The upper load distribution flange 34 may be constructed of a pluralityof independently formed arcuate segments 40 coupled together at theirends using tie plates 42, shown schematically, or using any othersuitable mechanical fastening elements, for example. The exemplary upperload distribution flange 34 shown herein includes four arcuate segments40, each forming an approximately 90 degree circumferential portion ofthe upper load distribution flange 34, though it will be appreciatedthat the upper load distribution flange 34 be constructed of more orfewer arcuate segments of various circumferential sizes in alternativeembodiments. In an exemplary alternative embodiment, the upper loaddistribution flange 34 may be formed as a single integral component thatdoes not include multiple independently formed arcuate segments.

Advantageously, the modular nature of the anchor cage 30, attributed inpart to the independently formed arcuate segments 40, facilitatesefficient transport of the anchor cage components to the wind turbineinstallation site. On the ground G at the installation site, eacharcuate segment 40 of the upper load distribution flange 34 may becoupled to a corresponding arcuate segment 40 of the base flange 38using a corresponding plurality of anchor bolts 36, thereby forming acircumferential portion of the anchor cage 30. The circumferentialportions of the anchor cage 30 may then be lowered into the excavationpit and joined together using the tie plates 42 for forming thecompleted anchor cage 30 within the excavation pit.

The upper load distribution flange 34 includes a plurality ofcircumferentially spaced bolt through bores 44 through which threadedupper ends 46 of the anchor bolts 36 are received. It will beappreciated that the base flange 38 includes a corresponding pluralityof bolt through bores 44 through which threaded lower ends 48 of theanchor bolts 36 are received. The bolt bores 44 are arranged into aradially inner ring 44 a for receiving a radially inner ring of theanchor bolts 36, and a radially outer ring 44 b for receiving a radiallyouter ring of the anchor bolts 36. The inner and outer rings 44 a, 44 bmay be radially aligned with one another such that the bolt bores 44 andrespective anchor bolts 36 are arranged into circumferential spacedradial pairs, as best shown in FIG. 2. Further, the bolt bores 44 may beuniformly spaced circumferentially such that each of the arcuatesegments 40 includes an equal quantity of bolt bores 44.

In exemplary embodiments, the anchor cage 30 may include approximately64 to 144 radial pairs of anchor bolts 36 and corresponding bolt bores44 formed on each of the upper load distribution flange 34 and baseflange 38. In the illustrated exemplary embodiment, the anchor cage 30includes 84 radial pairs of anchor bolts 36, such that each arcuatesegment 40 of the upper load distribution flange 34 and base flange 38includes 21 radial pairs of bolt bores 44. It will be appreciated thatvarious other suitable quantities of anchor bolts 36 and bolt bores 44may be provided in alternative embodiments.

The upper load distribution flange 34 further includes a plurality ofcircumferentially spaced fastening elements, shown in the form ofthreaded leveling through bores 50, that facilitate the leveling processdescribed below. Each fastening element defines a respective levelinglocation on the upper load distribution flange 34. While shown in theform of threaded through bores 50, the fastening elements may takevarious alternative forms suitable for engaging the exemplary levelingapparatus 82 described below. For example, the fastening elements may beprovided in the form of protrusions extending from the upper loaddistribution flange 34.

The leveling bores 50 may be arranged between the radially inner andouter rings 44 a, 44 b of the bolt bores 44, and may be provided withuniform circumferential spacing such that each arcuate segment 40 of theupper load distribution flange 34 includes an equal quantity of levelingbores 50. In the illustrated exemplary embodiment, the upper loaddistribution flange 34 includes twelve leveling bores 50 uniformlyspaced such that each arcuate segment 40 of the upper load distributionflange 34 includes three leveling bores 50. However, it will beappreciated that various alternative quantities and configurations ofleveling bores 50 may be provided. For example, less than twelveleveling bores 50 may be provided.

The upper load distribution flange 34 further includes a plurality ofcircumferentially spaced grouting through bores 52 through which grout,or other suitable cementitious materials, may be directed duringformation of the grout support layer 32, as described in greater detailbelow. Accordingly, each grouting bore 52 defines a respective groutinglocation on the upper load distribution flange 34.

Similar to the leveling bores 50, the grouting bores 52 may be arrangedbetween the radially inner and outer rings 44 a, 44 b of the bolt bores44, and may be provided with uniform circumferential spacing such thateach arcuate segment 40 of the upper load distribution flange 34includes an equal quantity of grouting bores 52. In the illustratedexemplary embodiment, the upper load distribution flange 34 includesfour grouting bores 52 uniformly spaced such that each arcuate segment40 of the upper load distribution flange 34 includes a grouting bore 52.However, various alternative quantities and configurations of groutingbores 52 may be provided. Furthermore, while the exemplary embodimentsshown and described herein include the use of bores 50 for levelingoperations and bores 52 for grouting operations, it will be appreciatedthat each of the bores 50, 52 may be used interchangeably as either aleveling bore or as a grouting bore.

As shown best in FIGS. 3A-4, each of the leveling bores 50 and groutingbores 52 may be positioned in radial alignment with a respective radialpair of the bolt bores 44. In an alternative exemplary embodiment, asshown in FIGS. 17-19 showing an arcuate segment 40 a of an alternativeexemplary upper load distribution flange, the leveling bores 50 andgrouting bores 52 may be positioned circumferentially between adjacentradial pairs of bolt bores 44.

Referring to FIGS. 5 and 5A, additional details of the anchor bolts 36and the manner in which they couple to the upper load distributionflange 34 and base flange 38 are described. As described above, theanchor cage 30 may be assembled in circumferential portions, eachincluding an arcuate segment 40 of the upper load distribution flange34, an arcuate segment 40 of the lower base flange 38, and a pluralityof anchor bolts 36 extending therebetween.

FIG. 5 shows a radial pair of anchor bolts 36 of a representativecircumferential portion of the anchor cage 30. Each anchor bolt 36extends longitudinally and includes a threaded upper end 46, a threadedlower end 48, and a central shank 54. Prior to assembling the anchorbolts 36 with the arcuate segments 40 of the upper load distributionflange 34 and base flange 38, the threaded upper end 46 of each anchorbolt 36 may be sealed with a protective covering 56, such as tape or aheat shrink hose for example, as shown in FIG. 5A.

During assembly, the threaded lower end 48 of the anchor bolt 36 ispassed through a bolt bore 44 of the arcuate segment 40 of the baseflange 38, and is secured thereto using upper and lower base nuts 58 andupper and lower base washers 60 that clamp the arcuate segment 40therebetween. The threaded upper end 46 of the anchor bolt 36 is passedthrough a corresponding bolt bore 44 of the arcuate segment 40 of theupper load distribution flange 34, and is secured thereto using an upperload distribution flange nut 62 and an upper load distribution flangewasher 64. Optionally, the portion of the anchor bolt 36 extendingbetween the upper load distribution flange 34 and the base flange 38 maybe encased within a protective tube 66, such as a PVC pipe or a heatshrink hose, for example. Advantageously, the protective tubes 66 andthe protective coverings 56 may substantially shield the anchor bolts 36from undesired contact and bonding with cementitious material during thepouring and curing steps described below.

As shown in phantom in FIG. 5, each of the leveling bores 50 and thegrouting bores 52 may be fitted with a plug, shown in the form of athreaded cover bolt 68. Advantageously, the plugs substantially shieldthe inner surfaces of the leveling bores and grouting bores 52 fromundesired contact and bonding with cementitious material during pouringand curing. In embodiments in which the plugs are in the form ofthreaded bolt 68, the grouting bores 52 may be threaded similarly to theleveling bores 50 for threadedly receiving the cover bolts 68.

Referring to FIG. 6, a radial pair of support sleeves 70 may besubstituted for the protective tubes 66 at select circumferentiallocations within the anchor cage 30, for enhancing internal structuralsupport within the foundation 26. In an exemplary embodiment, a radialpair of support sleeves 70 may be arranged at approximately every tenthradial pair of anchor bolts 36, for example. The support sleeves 70 areformed of a material having a high compressive strength suitable forload bearing applications, such as steel, for example. Additionally,each support sleeve 70 is formed with an outer diameter that is largerthan the diameters of the bolt bores 44 formed in the load distributionflange 34 and the base flange 38. Advantageously, in addition toshielding the anchor bolts 36 encased therein from undesired contact andbonding with cementitious material, the support sleeves 70 furtherfunction to support the weight of the upper load distribution flange 34and ensure that a uniform spacing between the upper and lower flanges34, 38 is substantially maintained prior to the addition of concrete, asdescribed below.

Referring to FIGS. 2 and 7, once the circumferential portions of theanchor cage 30 have been joined together within the excavation pit usingtie plates 42, final positional adjustments of the assembled anchor cage30 may be made to ensure generally central positioning within theexcavation pit. The excavation pit may be lined with a form (not shown),such as large diameter piping, for defining an outer side surface of thefoundation 26.

Following final positioning of the anchor cage 30 within the excavationpit, a cementitious material, such as concrete, is poured into theexcavation pit so that the pit fills up to approximately an uppersurface 78 of the upper load distribution flange 34. Accordingly, theanchor cage 30 is substantially embedded within the cementitiousmaterial. The poured cementitious material is then allowed a suitablelength of time to adequately cure to form a rigid body 28, shown in FIG.7. In an exemplary embodiment, the cementitious material may be allowedapproximately 48 hours to cure.

As shown in FIG. 7, the protective tubes 66 and cover bolts 68substantially shield the anchor bolts 36, leveling bores 50, andgrouting bores 52 from undesired contact with the cementitious material.Prior to pouring the cementitious material, lower and side surfaces ofthe upper load distribution flange 34 may be coated with a lubricant,such as oil or paint for example, to facilitate separation of the upperload distribution flange 34 from the rigid body 28 for a subsequentleveling operation, described below.

Referring to FIGS. 8-11, steps for leveling the upper load distributionflange 34 according to an exemplary embodiment of the invention areshown. As described above, it is desirable to position the upper loaddistribution flange 34 in a leveled orientation in order to provide alevel mounting surface for the wind turbine 10 during installation. Itis also desirable to provide a grout support layer between the upperload distribution flange 34 and the rigid body 28 in order to facilitateload transfer from the wind turbine 10 to the foundation 26, whilemaintaining a rigid metal-to-metal interface between the foundation 26,via the upper load distribution flange 34, and the wind turbine 10.Advantageously, the exemplary embodiments of the invention describedbelow provide steps and components for achieving these objectives.

FIGS. 8-11 show a representative leveling location on the upper loaddistribution flange 34, including a leveling bore 50 and an adjacentradial pair of anchor bolts 36 and upper load distribution flange nuts62. It will be understood that the leveling steps described below may besimilarly performed at each of the other leveling locations defined bythe remaining leveling bores 50.

First, the upper load distribution flange 34 at its upper surface 78 isevaluated for any degree of slope relative to horizontal that must becorrected during leveling. Next, the height and angular orientation of alevel (horizontal) mounting plane M (see FIGS. 9-11) to which the upperload distribution flange 34 is to be elevated, for example in order toadequately correct any undesired sloping, is determined. Thisdetermination may be performed using various known devices, such as alaser level, for example.

As shown in FIG. 8, all of the upper load distribution flange nuts 62 onthe upper load distribution flange 34 are then loosened and rotatedalong their respective anchor bolts 36 to suitable heights, relative tothe upper surface 78 of the upper load distribution flange 34, so as tocollectively define a level (horizontal) reference plane P parallel tothe level mounting plane M. An offset of the level reference plane Pfrom the level mounting plane M may be chosen based on a correspondingdimension of a leveling apparatus to be used for leveling the upper loaddistribution flange 34, as described in greater detail below. It will beunderstood that in installations in which the predetermined level planesM, P are sloped relative to the upper surface 78 of the loaddistribution flange 34 recessed within the rigid body 28, the upper loaddistribution flange nuts 62 may be positioned at differing heightsrelative to the upper surface 78 in order to define the level(horizontal) reference plane P. For example, at a given levelinglocation having a radial pair of upper load distribution flange nuts 62,a first upper load distribution flange nut 62 may be elevated to a firstheight and a second upper load distribution flange nut 62 may beelevated to a second height. In an exemplary embodiment, each of theupper load distribution flange nuts 62 at the leveling locations may beelevated to a height of approximately 50 mm relative to the highestpoint of the upper load distribution flange 34, and then individuallyadjusted as necessary to define the level plane P.

Referring to FIGS. 9 and 9A, a plurality of leveling apparatuses 82according to an exemplary embodiment of the invention may be used at theplurality of leveling locations to elevate the upper load distributionflange 34 from the rigid body 28 up to the level mounting plane M. Eachleveling apparatus 82 includes a leveling device shown in the form of aleveling plate 84, a connecting element shown in the form of a threadedleveling rod 86, and an actuating element shown in the form of aleveling nut 88. Prior to installation of the leveling apparatuses 82,the cover bolts 68 (FIG. 7) are removed from the leveling bores 50 onthe upper load distribution flange 34.

As shown best in FIG. 9A, the exemplary leveling plate 84 of eachleveling apparatus 82 includes an upper plate portion 90 and first andsecond side plate portions 92, 94 depending downwardly from the upperplate portion 90 and parallel to one another. The upper plate portion 90includes first and second through bores 96 sized and spaced from oneanother to slidably receive therethrough the threaded upper ends 46 of aradial pair of anchor bolts 36 at a leveling location. As shown, each ofthe first and second through bores 96 may be formed with an oblongcross-sectional shape for accommodating a range of radial spacingsbetween the inner and outer anchor bolts 36 of a radial pair.

The upper plate portion 90 of the leveling plate 84 further includes athird through bore 98 sized to slidably receive therethrough thethreaded leveling rod 86 of the leveling apparatus 82. The third throughbore 98 is suitably positioned for alignment with a leveling bore 50 atany one of the leveling locations on the upper load distribution flange34. As such, it will be appreciated that the positioning of the thirdthrough bore 98 relative to the first and second through bores 96 issimilar to the positioning of a leveling bore 50 on the upper loaddistribution flange 34 relative to an adjacent radial pair of anchorbolts 36. For example, in the exemplary embodiment in which the levelingbores 50 are positioned in radial alignment with a pair of bolt bores44, and corresponding anchor bolts 36, the third through bore 98 of theleveling plate 84 is similarly positioned in alignment with the firstand second through bores 98. In alternative embodiments in which theleveling bores 50 are circumferentially spaced between adjacent pairs ofanchor bolts 36, i.e., not in radial alignment with a pair of anchorbolts 36, the third through bore 98 of the leveling plate 84 issimilarly spaced from the first and second through bores 96, such asshown by the alternative exemplary leveling plate 84 a shown in FIG. 18.

While the exemplary leveling plates 94, 94 a shown herein include asingle grouping of first and second through bores 96 and third throughbore 98, leveling plates of alternative embodiments may include multipleadjacent groupings of through bores 96, 98. For example, a levelingplate may include two adjacent rows of through bores, each row havingfirst and second through bores 96 and a third through bore 98 positionedtherebetween. Furthermore, the through bores 96, 98 of one or more ofthe multiple rows may each be formed with a suitable oblong, orotherwise non-circular, shape for accommodating load distributionflanges of various diameters.

As shown in FIG. 9 in connection with a representative leveling locationdefined by a leveling bore 50, the leveling plate 84 is fitted over theradial pair of anchor bolts 36. In particular, the threaded upper ends46 of the anchor bolts 36 extend through the first and second throughbores 96 of the leveling plate 84, and the third through bore 98 alignswith the leveling bore 50. The leveling plate 84 is lowered so that alower surface of the upper plate portion 90 rests on top of the elevatedupper load distribution flange nuts 62. Advantageously, the levelingplate 84 is not directly attached to the upper load distribution flange34. Prior to or following application of the leveling plate 84, a lowerend of the leveling rod 86 is threaded into the leveling bore 50, and anupper end of the leveling rod 86 is received through the third throughbore 98 of the leveling plate 84.

As illustrated by the movement arrows shown in FIG. 9, the leveling nut88 at each leveling location is threaded onto the leveling rod 86 andtightened against the upper surface of the upper plate portion 90 of theleveling plate 84. As the leveling nuts 88 at the plurality of levelinglocations are slowly rotated further, the leveling rods 86 are graduallydrawn upwardly through the leveling plates 84, thereby raising the upperload distribution flange 34 from the rigid body 28 and along the anchorbolts 36, which function as linear guides. Meanwhile, the levelingplates 84 and upper load distribution flange nuts 62 remain stationaryin fixed positions relative to the anchor bolts 36. Advantageously, theleveling nut 88 at each leveling location is easily accessed forrotation and does not contact either of the adjacent anchor bolts 36. Itwill be appreciated that the alternative exemplary leveling plate 84 aof FIGS. 18 and 19 functions in a manner similar to leveling plate 84.

The upper load distribution flange 34 may be formed with angled sidesurfaces 100, 102 that, in combination with the lubricant applied to theupper load distribution flange 34 surfaces prior to pouring thecementitious material for forming the rigid body 28, facilitateseparation of the upper load distribution flange 34 from the rigid body28. In particular, the upper load distribution flange side surfaces 100,102 may be angled such that the upper load distribution flange 34 isformed with larger radial width at its upper surface than at its lowersurface.

While the connecting element and the actuating element of the levelingapparatus 82 are shown herein in the form of threaded rod 86 and nut 88that threadedly engages and rotates relative to threaded rod 86, it willbe appreciated that these components may take various alternative formsand cooperate in various alternative manners suitable for lifting theupper load distribution flange 34 relative to the rigid body 28. In thisregard, the connecting element may take any form suitable for couplingthe leveling apparatus 82 to the upper load distribution flange 34 andfor guiding actuation of the actuating element. Moreover, while rotationis the primary manner of actuation of the actuating element disclosedherein, various alternative manners of actuation may be suitably used.For example, in an exemplary alternative embodiment the actuatingelement may slide linearly along the connecting element, withoutrotation.

As shown in FIGS. 9 and 10, the lower surfaces of the side plateportions 92, 94 of the leveling apparatuses 82 collectively define thelevel mounting plane M, which may be positioned at a predeterminedheight h relative to the pre-elevated position of the upper loaddistribution flange 34. Accordingly, at each leveling location, theleveling nut 88 is tightened on the leveling rod 86 until the uppersurface of the upper load distribution flange 34 contacts the lowersurfaces of the side plate portions 92, 94. In this regard, it will beunderstood that the length of the side plate portions 92, 94, in adirection perpendicular to the upper plate portion 90, define the offsetdistance between the level mounting plane M and the level referenceplane P at which the upper load distribution flange nuts 62 arepositioned.

Referring now to FIGS. 11-15, a grouting operation performed at theplurality of grouting locations on the upper load distribution flange 34is described according to an exemplary embodiment of the invention.Following leveling of the upper load distribution flange 34 describedabove, and prior to the grouting operation described below, the upperload distribution flange nuts 62 positioned at non-leveling locationsmay be hand-tightened against the upper surface 78 of the upper loaddistribution flange 34, as shown in FIG. 11 at a representative groutinglocation.

When raising the upper load distribution flange 34 up to the levelmounting plane M during the leveling operation described above, a trough104 in the rigid body 28 is exposed. As such, the upper loaddistribution flange 34 functions in part as a template for forming thetrough 104 in the rigid body 28. In exemplary embodiments, the upperload distribution flange 34 may be raised to a level mounting plane M soas to create a trough 104 having a depth in the range of approximately 8mm to 50 mm, such as approximately 25 mm, for example. As describedbelow, while the upper load distribution flange 34 is suspended at thelevel mounting plane M by the leveling apparatuses 82, high strengthgrout 106 is directed into the trough 104 and cured to form groutsupport layer 32 for supporting the upper load distribution flange 34 atthe level mounting plane M. It will be appreciated that various suitablecementitious materials other than grout may be used for forming thesupport layer 32 in alternative embodiments.

FIG. 11 shows a representative grouting location on the upper loaddistribution flange 34, defined by one of the grouting bores 52. Aleveling plate 84 at an adjacent leveling location is shown in phantom.It will be understood that the grouting steps described below may besimilarly performed at each of the other grouting locations defined bythe remaining grouting bores 52, simultaneously or sequentially, forexample. Prior to grouting, the cover bolts 68 fitted in the groutingbores 52 are removed to provide access to the trough 104 via thegrouting bores 52. Additionally, water may be directed into the trough104 for hydrating the grout 106 directed into the trough 104 thereafter.

As shown in FIGS. 12-14, an exemplary grout delivery device shown in theform of a funnel-like hopper 108 may be used for delivering grout 106into the trough 104 via a grouting bore 52. The hopper 108 generallyincludes a reservoir 110 for holding a supply of grout 106, and anelongate stem 112 extending from the reservoir 110 for directing thegrout 106 through the grouting bore 52 and into the trough 104. The stem112 is formed with a length suitable to provide the grout 106 flowingfrom the hopper 110 with a hydrostatic pressure sufficient to fill thetrough 104 at each grouting location. A distal end 114 of the stem 112may be formed with an outer diameter that is smaller than a diameter ofthe grouting bore 52, such that at least a portion of the distal end 114may be received within the grouting bore 52. Using one or more hoppers108, grout is directed into the trough 104 at each grouting locationuntil the grout 106 seeps out from the trough 104 at the outer and innercircumferences of the upper load distribution flange 34. It will beappreciated that the hopper 108 may have various alternativeconfigurations other than the one shown herein. Moreover, it will beappreciated that the grout delivery device may take various alternativeforms, such as an injection device (not shown), which may include apump, for example.

Referring to FIG. 15, the grout 106 directed into the trough 104 isallowed a suitable length of time to adequately cure, such as up toapproximately 28 days, for example. Curing of the grout 106 forms agrout support layer 32 between the rigid body 28 and the leveled upperload distribution flange 34. Advantageously, the grout support layer 32supports the upper load distribution flange 34 at the level mountingplane M, such that the leveling apparatuses 82 may be removed.Accordingly, the completed foundation 26 includes a rigid body 28reinforced by the anchor cage 30, and a grout support layer 32 thatsupports a leveled upper load distribution flange 34. Prior to mountingthe wind turbine 10 to the foundation 26, the upper load distributionflange nuts 62 and washers 64 provided on the threaded upper ends 46 ofthe anchor bolts 36 are removed.

Referring to FIG. 16, the wind turbine 10 is coupled to the foundation26 by aligning mounting bores 116 in the lower tower flange 24 with thethreaded upper ends 46 of the anchor bolts 36. The wind turbine tower 12is then lowered until the tower flange 24 directly contacts and issupported by the upper load distribution flange 34. Sets of upper loaddistribution flange nuts 62 and washers 64, which may be new sets notused during formation of the foundation 26, are then applied to thethreaded upper ends 46. The upper load distribution flange nuts 62 arethen tightened with a suitable torque. In this manner, the anchor bolts36 are post-tensioned and maintain the rigid body 28 of the foundation26 under high compression, thereby enabling the foundation 26 tosuitably withstand various forces and moments exerted by the windturbine 10 during operation.

While the present invention has been illustrated by the description ofvarious embodiments thereof, and while the embodiments have beendescribed in considerable detail, it is not intended to restrict or inany way limit the scope of the appended claims to such detail. Thevarious features discussed herein may be used alone or in anycombination. Additional advantages and modifications will readily appearto those skilled in the art. The invention in its broader aspects istherefore not limited to the specific details and illustrative examplesshown and described. Accordingly, departures may be made from suchdetails without departing from the scope of the general inventiveconcept.

1. A method of forming a wind turbine foundation, comprising: providingan anchor cage in an excavation pit formed in a ground surface, theanchor cage including an upper flange, a lower flange, and a pluralityof anchor bolts extending between the upper and lower flanges; directinga first cementitious material into the excavation pit so that the anchorcage becomes at least partially embedded within the first cementitiousmaterial; allowing the first cementitious material to cure to form arigid body; selectively engaging a connecting element with the upperflange and positioning an actuating element in operative relation withthe connecting element, the connecting element and the actuating elementpositioned in non-contact relation with the anchor bolts; actuating theactuating element relative to the connecting element and thereby raisingthe upper flange from the rigid body into a leveled position; directinga second cementitious material into a space beneath the raised upperflange; and allowing the second cementitious material to cure to form asupport layer.
 2. The method according to claim 1, further comprising:selectively positioning a plurality of nuts along threaded ends ofrespective anchor bolts such that the nuts collectively define a levelplane, wherein raising the upper flange into a leveled position includespositioning the upper flange parallel to the level plane while the nutsremain stationary relative to the anchor bolts.
 3. The method accordingto claim 1, wherein actuating the actuating element relative to theconnecting element includes rotating the actuating element.
 4. Themethod according to claim 3, wherein rotating the actuating elementrelative to the connecting element includes rotating a nut relative to athreaded rod coupled to the upper flange.
 5. The method according toclaim 1, further comprising: providing at least one leveling device at aposition spaced above the upper flange, the at least one leveling devicebeing supported on the anchor bolts, wherein raising the upper flangeinto a leveled position includes raising the upper flange to contact theleveling device.
 6. The method according to claim 1, wherein the upperflange is circular and actuating the actuating element includes rotatinga plurality of circumferentially spaced threaded elements, the threadedelements positioned at circumferential positions along the upper flange.7. The method according to claim 1, wherein the upper flange includes aplurality of bores and directing the second cementitious material intothe space beneath the raised upper flange includes directing the secondcementitious material through the bores.
 8. A method of erecting a windturbine including a tower having a lower portion, comprising: forming awind turbine foundation according to claim 1; and coupling the lowerportion of the wind turbine to the anchor bolts.
 9. The method accordingto claim 8, wherein coupling the lower portion of the wind turbine tothe anchor bolts includes supporting the wind turbine on the upperflange and supporting the upper flange on the support layer.
 10. Asystem for forming a wind turbine foundation, comprising: an anchor cageincluding an upper flange, a lower flange, and a plurality of anchorbolts extending between the upper and lower flanges, the upper flangeconfigured to engage a lower portion of a wind turbine; and at least oneleveling apparatus including a connecting element engageable with theupper flange, and an actuating element operatively associated with theconnecting element, whereby the at least one leveling apparatus isoperated to raise the upper flange to a leveled position, includingengaging the connecting element with the upper flange and actuating theactuating element relative to the connecting element without contactingthe anchor bolts with the actuating element.
 11. The system according toclaim 10, wherein the actuating element is rotatable relative to theconnecting element for raising the upper flange to the leveled position.12. The system according to claim 11, wherein the connecting elementincludes a threaded rod and the actuating element includes a nut. 13.The system according to claim 10, wherein the at least one levelingapparatus includes a plurality of leveling apparatuses, and the upperflange includes a plurality of fastening elements that each engage arespective one of the connecting elements for raising the upper flangeto a leveled position.
 14. The system according to claim 13, wherein theplurality of fastening elements include threaded bores, and theconnecting element of each leveling apparatus is configured tothreadedly engage a respective one of the threaded bores.
 15. The systemaccording to claim 10, wherein the upper flange includes a plurality ofbores through which a cementitious material is directed into a spacebeneath the upper flange.
 16. The system according to claim 15, furthercomprising: a material delivery device that directs the cementitiousmaterial into the space beneath the upper flange, the material deliverydevice including a stem that engages at least one of the plurality ofbores for directing the cementitious material therethrough.
 17. Thesystem according to claim 10, the at least one leveling apparatusfurther including a leveling plate having an upper plate portion and atleast one side plate portion, wherein the connecting element includes athreaded rod and the actuating element includes a nut, the upper plateportion includes first and second through bores for receiving respectiveupper ends of a pair of the anchor bolts therethrough, and a thirdthrough bore for receiving the threaded rod therethrough, and thethreaded rod is engageable with the upper flange, the leveling plate ispositionable relative to the upper flange such that the at least oneside plate portion defines a level plane, and the nut is rotatablerelative to the threaded rod and the leveling plate to raise the upperflange to contact the at least one side plate portion and therebyposition the upper flange in the level plane.